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LLM, HTTP, Code, and Tool nodes support error handling out-of-box. When a node fails, it can take one of the three behaviors below:
The default behavior. When a node fails, the whole workflow stops. You get the original error message.Use this when:
  • You’re testing and want to see what broke
  • The workflow can’t continue without this step
When a node fails, use a backup value instead. The workflow keeps running.Requirements
  • The default value must match the node’s output type — if it outputs a string, your default must be a string.
ExampleYour LLM node normally returns analysis, but sometimes it fails due to rate limits. Set a default value like:
"Sorry, I'm temporarily unavailable. Please try again in a few minutes."
Now users get a helpful message instead of a broken workflow.
When a node fails, trigger a separate flow to handle the error.The fail branch is highlighted in orange. You can:
  • Send error notifications
  • Try a different approach
  • Log the error for debugging
  • Use a backup service Example
Your main API fails, so the fail branch calls a backup API instead. Users never know there was a problem.

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Error in Loop/Iteration Nodes

When child nodes fail inside loops and iterations, these control flow nodes have their own error behaviors. Loop nodes always stop immediately when any child node fails. The entire loop terminates and returns the error, preventing any further iterations from running. Iteration nodes let you choose how to handle child node failures through the error handling mode setting:
  • terminated - Stops processing immediately when any item fails (default)
  • continue-on-error - Skips the failed item and continues with the next one
  • remove-abnormal-output - Continues processing but filters out failed items from the final output
When you set an iteration to continue-on-error, failed items return null in the output array. When you use remove-abnormal-output, the output array only contains successful results, making it shorter than the input array.

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Error variables

When using default value or fail branch, you get two special variables:
  • error_type - What kind of error happened (see Error Types)
  • error_message - The actual error details
Use these to:
  • Show users helpful messages
  • Send alerts to your team
  • Choose different recovery strategies
  • Log errors for debugging
Example 
{% if error_type == "rate_limit" %}
Too many requests. Please wait a moment and try again.
{% else %}
Something went wrong. Our team has been notified.
{% endif %}